The GY401 has to be set via TX, there is no way to do it on the gyro it's self (in terms of gyro gain)

On the Eclipse 7, there is several different flight modes. Generally, if you setup one flight mode with a gyro gain over 50% and one flight mode with a gyro gain below 50%, switching between the two will allow you to switch between AVCS and Normal(rate) mode. Then simply adjust gyro sensitivity as nescesary in whatever mode you pick. For example, I switch between normal mode and ST1 mode to switch gyro operation.

Also, the gyro must be powered on in AVCS (heading hold) mode and then switched. So, for example, if you've got norm set to 75% gyro gain, turn the transmitter and gyro on in that mode, then switch to rate mode if you need to on ST (or whatever you set it to). It would've been a whole lot easier all things considered if the eclipse 7 had a gyro switch, but alas, you gotta work around such things

The futaba gyro instructions are awful, theres a good guide online, have a look at this:
http://www.coloradorotorheads.com/articles/401.htm

It should help explain alot of stuff.